Lightning arrester constructions



1961 w. H. NASH ,971,132

LIGHTNING ARRESTER CONSTRUCTIONS Filed June 30, 1958 2 Sheets-Sheet 1 D FH e- 4 I 39 T '43 44 l 44 43 i i \NVENTOR W\LL.\AM H.NAsH

T 1b BY ATTORNEY Feb. 7, 1961 w, NASH LIGHTNING ARRESTER CONSTRUCTIONS 2 Sheets-Sheet 2 Filed June 30, 1958 \HVENTOR \N\\.\.\A-\ H. NASH ATTORNEY United States Patent LIGHTNING ARRESTE'R CONSTRUCTIONS William H. Nash, South Milwaukee, Wis., assignor to McGraw Edison Company, Milwaukee, Wis., 21 corporation of Delaware Filed June '30, 1958, Ser. No. 745,732

7 Claims. (Cl. 31766) This invention relates. to lightning arrester constructions.

In lightning arresters it sometimes happens that where a valve type arrester is employed in series with either a multiple or single spark gap, when an excessively large surge occurs followed by follow current, that the valve material is damaged and becomes permanently conductive. Under these conditions the damaged arrester constitutes a dead short across the power supply and would have to be removed.

Attempts have been made to provide a gap external to the lightning arrester and in series therewith so as to provide an additional gap in an attempt to isolate a damaged lightning arrester from the line. These attempts have not proved wholly satisfactory for if the gap is large enough to afford the desired protection for a damaged lightning arrester, it alters the characteristics of the arrester very greatly and makes the arrester, under nor- 'mal conditions, responsive only to excessively high voltage surges as the current will have to jump the large external gap as well as the internal gap of the valve type lightning arrester.

This invention is designed to overcome the above noted defects and objects of this invention are to provide a fused gap lightning arrester of the valve type which is so constructed that when the lightning arrester is damaged, as outlined hereinabove, it will automatically remove or isolate such damaged arrester from the line for normal operating conditions but will still serve to give protection to the circuit against abnormally high voltage surges.

Further objects are to provide a li htning arrester which has all of the above noted features and yet does not in any way alter the characteristics of the arrester under normal conditions.

In further detail objects of this invention are to provide a lightning arrester construction in which a relatively large external gap is provided but which is normally shunted by a fuse, and in which a valve type ligh ning arrester is connected in series with the fused spark gap, and in which when the arrester is damaged from an excessively large surge or high voltage surge, the arrester is effectively removed from the circuit and isolated by the melting of the fuse, and in which the distance or length of the normally effective gap in the arrester is predetermined.

Further objects of this invention are to provide a lightning arrester construction which is eminently suited for connection in shunt with a high voltage primary of a transformer or with other electrical devices, in which the electrical device is normally protected by the lightning arrester which responds to a reasonably low voltage surge so that it does not require an abnormally high voltage in order to cause the spill gap or external gap to function, and yet in which after the arrester has been damaged, the external gap functions in the capacity of a spill gap, although a relatively large spill gap, and in which the transformer or other device is protected when 2,971,132 Patented Feb. 7, 1961 ice subjected to a high voltage surge sufficient to cause the external gap to function as a spill gap.

Further objects are to provide a construction of lightning arrester and fused spark gap which is relatively simple and may be easily installed and which is thoroughly reliable in operation.

Embodiments of the invention are shown in the accompanying drawings, in which:

Figure l. is an elevation of the lightning arrester with the external fused gap.

Figure 2 is a detail sectional view taken on the line 2-2 of Figure 1.

Figure 3 is a view of a lightning arrester and a portion of a transformer with parts broken away and in section, showing a further form of lightning arrester construction.

Figure 4 is a wiring diagram for the apparatus.

Referring to the drawings particularly Figures 1 and 2 it will be seen that a valve type lightning arrester having internal spark gaps in series therewith is indicated by the reference character 1. The construction of the arrester may be of that general type in which valve material is provided in series with one or more spark gaps. The valve arrester 1 is connected at its lower terminal 2 to the ground and is supported in any suitable manner, as by means of the support 3. The upper end of the valve arrester carries a spacing insulator 4 provided at its upper end with an upper terminal indicated generally by the reference character 5. This upper terminal is connected directly to the line 6, usually a high voltage line.

A spark gap is provided between the upper terminal of the lightning arrester indicated generally by the reference character 7 and supports one electrode 8 of a relatively large external spark gap or spill gap 10. The other electrode 9 of the gap 1% is supported from the terminal 5 hereinabove described.

The gap 10 between the electrodes 3 and 9 is relatively large and is normally bridged by means of a fuse link 11. The fuse link is provided with terminal members, such as eyelets 12, which may be grasped by the lineman in placing the fuse in position. It is also provided with a pair of spaced collars or similar members 13, 13. Preferably the fuse link 11 is housed within a fiber tube or other type of tube indicated by the reference character 14 so that the fusible portion 15 of the link is housed within such tube. The link is connected to the relatively stiff projecting portions 16, 16 which are provided with the eyelets 12 and with the collars 13, 13 previously described. The upper terminal 5 is provided with an arm 17 having a notch 19 which is adapted to receive the left hand end of the fuse link as viewed in Figure 1 and to have the collar 13 fitted behind the curved or dished portion of the arm 17. Similarly, a second arm 18, though of spring material, is supported from the electrode 8. This arm 18 is also notched at its upper end as described for the arm 17 and, as stated, is of springy material so that when released it will occupy the dotted line position shown in Figure 1.

It will be seen that the fuse link 15 is placed under tension and when it blows or melts the arm 18 will throw one end of the remaining portion of the fuse link outwardly and the other arm 17, which may be rigid or may be springy, will by reaction, throw the left hand end of the fuse link away.

It will be seen that normally the relatively large spark gap 10 between the electrodes 8 and 9, is bridged directly or shunted by means of the fuse link 11 and therefore the lightning arrester 1 functions in its normal capacity without having any of its characteristics altered since it is connected conductively directly with the high voltage line 6. It will be seen that when a surge occurs under normal conditions nothing happens to the fuse link 11.

Under normal conditions the valve type lightning arrester does not have its characteristics altered as the external or auxiliary gap is bridged by the fuse and the lightning arrester operates in its normal manner. However, when the arrester clinkers or breaks down, the fuse blows. It is heated up enough to blow under these conditions whereas under normal lightning strokes and surges, as long as the arrester is intact, the fuse does not blow.

It is to be noted that the fuse in this invention is not intended to clear fault currents. its purpose is to increase the spacing of the arrester gap so that after the fault through a damaged arrester is cleared by a circuit interrupter, the gap is sufiicient to prevent reestablishing the current through the arrester.

In addition to the above, a degree of protection is still provided by the damaged arrester.

It is to be understood that the electrical instrumentality, such as the transformer for instance, is connected directly in shunt with the lightning arrester 1 and spark gap 10.

This construction is shown in greater detail in Figure 3 which ShOWs another form that the invention may take. In Figure 3 it will be seen that a transformer has been indicated by the reference character and has its high voltage terminal indicated generally by the reference character 21. This high voltage terminal carries one of the two electrodes 22, 23 of the relatively large spark gap indicated by the reference character 24. The other electrode 23 is supported by the upper terminal '25 of the valve type lightning arrester. The arms or electrodes 22, 23 are notched as shown in Figure 2 for the first'form of the invention and a tensioned fuse link indicated generally by the reference character 26 is supported from the arms. The arms or electrodes 22, 23 may have upturned portions indicated at 2'7 and 28, which are notched as in Figure 2 and receive the fuse link.

The fuse link consists of a fusible section 29 connected between the relatively stiff members 31, 31 of this spring tension fuse link. The ends of the members 31, 31 are provided with knobs or hand portions. Springs 32 are positioned between the knobs 31 and the upturned portions 27, 28 of the electrodes 22 and 23 so as to tension the fuse link. The fuse link, as stated, includes the member 29 which may be a relatively fine or small sized piano wire and which is bridged by means of a fusible portion 33.

It is to be understood that when ordinary surges occur they are discharged through the lightning arrester indicated generally by the reference character 34 to the ground. The arrester 34 is provided with an upper terminal as stated which is connected through the link 26 to the upper terminal '21 of the transformer 20 so that the lightning arrester 34 and the transformer Ztl are positioned in shunt between the high voltage line 35 and the ground, the lower terminal 36 of the lightning arrester 34 being connected to the ground. The lightning arrester 34 is of the conventional type provided with valve material 37 and with the internal spark gap 33'.

A Wiring diagram is shown in Figure 4 and it will be seen that a transformer indicated generally by the reference character 39 has been shown having its primary connected between the mains 4t 41. Obviously if this is a single bushing transformer the lower terminal of the ground bushing would be connected directly to the ground and the upper terminal to the live main.

When the construction shown in Figure 4 is employed a lightning arrester is connected on each side of the lead in conductors 42 for the transformer 39 These lightning arresters are indicated by the reference character 43, 43 and are connected through the relatively large spark gap indicated generally at 44-, 44- to the two lead in conductors 42, 42. The external or auxiliary gaps 44, 414 are bridged by means of the fuse links 45, 45.

It will be seen that when an ordinary lightning surge occurs, the lightning arrester discharges the surge to the ground in the usual manner, the external gap being bridged by means of the fuse link. However, when the lightning arrester is damaged and the valve material fuses together, a direct connecting path from the lower end of the internal spark gap assembly of the lightning arrester to the ground results. Under these conditions the external fuse link Will blow and will place the relatively large external gap in series with the damaged lightning arrester and thus, in eifecb will remove the lightning arrester from the line.

To recapitulate, under normal conditions this relatively large external gap does not alter the characteristics of the arrester at all. But after the arrester has been damaged and is in reality a dead short across the supply means, the relatively large spark gap is then effectively interposed in series with the damaged lightning arrester. When zero voltage occurs at the relatively large spark ga due to opening of a preceding circuit interrupter, the arc is extinguished and will not be reestablished under normal conditions and therefore there will be no follow current passing across the relatively large spark gap through the damaged arrester.

It will also be seen that the normal functioning and characteristics of the lightning arrester are not altered in any way by the relatively large gap.

It is to be seen further that the relatively large spark gap, though offering a higher breakdown voltage than that of a smaller spark gap, will nevertheless furnish a degree of protection as it will operate as a spill gap for discharging an excessively high voltage surge through the damaged lightning arrester.

It will be seen further that the construction is relatively simple and is cheap and easy to install.

Although this invention has been described in considerable detail it is to be understood that such description is intended as illustrative rather than limiting as the invention may be variously embodied and is to be interpreted as claimed.

I claim:

1. A valve type lightning arrester comprising an insulating casing having a first terminal and a second terminal, valve material and an internal spark gap connected in series between said terminals, a third terminal spaced from said first terminal, a first and a second electrode connected respectively to said first and third terminals and spaced apart to form a relatively large external spark gap as compared with said internal spark gap, and a fuse link normlly bridging said relatively large external spark gap and arranged to be ruptured if said valve material becomes clinkered, the large external spark gap being arranged to stay in series circuit with the internal spark gap for both a lightning surge of normal value and for an abnormal lightning surge of sntficient value to cause clinkering of the valve material, and the fuse link being arranged to melt upon the occurrence of an abnormal lightning surge of a value suflicient to cause clinkering of the valve material.

2. A valve type lightning arrester comprising an insulating casing having a first terminal and a second terminal, valve material and an internal spark gap connected in series between said terminals, a third terminal spaced from said first terminal, a first and a second electrode connected respectively to said first and said third terminals and spaced apart to form a relatively large external spark gap as compared with said internal spark gap, and a tensioned fuse link normally bridging said relatively large external spark gap and arranged to be ruptured if said valve material becomes clinkered, the large external gap being arranged to stay in series circuit with the internal spark gap'for both a lightning surge of normal value and for an abnormal lightning surge of suflicient value to cause clinkering of the valve material, and the fuse link beingarranged to melt upon the occurrence of an abnormal lightning surge of a value suflicient to cause clinkering of the valve material.

3. A valve type lightning arrester comprising an insulating casing having a first terminal and a second terminal, valve material and an internal spark gap connected in series between said terminals, a third terminal spaced from said first terminal, a first and a second electrode connected respectively to said first and third terminals and spaced apart to form a relatively large external spark gap as compared with said internal spark gap, and a fuse link normally bridging said relatively large external spark gap and arranged to be ruptured if said valve material becomes clinkered, one of said electrodes being resilient and biased outwardly for tensioning said fuse link, the large external spark gap being arranged to stay in series circuit with the internal spark gap for both a lightning surge of normal value and for an abnormal lightning surge of sufficient value to cause clinkering of the valve material, and the fuse link being arranged to melt upon the occurrence of an abnormal lightning surge of a value suflicient to cause clinkering of the valve material.

4. A valve type lightning arrester comprising an insulating casing having terminals and having valve material and an internal spark gap located within said casing and connected in series between said terminals, an external spark gap connected in series with said lightning arrester and being relatively large as compared with said internal spark gap, and a fuse link normally bridging said external spark gap, the large external spark gap being arranged to stay in series circuit with the internal spark gap for both a lightning surge of normal value and for an abnormal lightning surge of sufiicient value to cause clinkering of the valve material, and the fuse link being arranged to melt upon the occurrence of an abnormal lightning surge of a value sul'licient to cause clinkering of the valve material.

5. A valve type lightning arrester comprising an insulating casing having terminals and having valve material and an internal spark gap located within said casing and connected in series between said terminals, an external spark gap connected in series with said lightning arrester and being relatively large as compared with said internal spark gap, and a tensioned fuse link normally bridging said external spark gap, the large external spark gap being arranged to stay in series circuit with the internal spark gap for both a lightning surge of normal value and for an abnormal lightning surge of sufiicient value to cause clinkering of the valve material, and the fuse link being arranged to melt upon the occurrence of an abnormal lightning surge of a value sufficient to cause clinkering of the valve material.

6. An electrical construction for protection against lightning surges, a power line, an electrical instrumentality supplied from said power line and having a terminal connected to said power line, a first electrode carried by said terminal, a valve type lightning arrester comprising insulating supporting means including an insulating casing having a first and a second terminal and having valve material and an internal spark gap connected in series between said first and second terminals and located within said casing, a second electrode carried by said first terminal of said lightning arrester and spaced from said first electrode and constituting with said first electrode a large external spark gap as compared with said internal spark gap, and a fuse link normally bridging said large external spark gap, the large external spark gap being arranged to stay in series circuit with the internal spark gap for both a lightning surge of normal value and for an abnormal lighting surge of sufiicient value to cause clinkering of the valve material, and the fuse link being arranged to melt upon the occurrence of an abnormal lightning surge of a value suificient to cause clinkering of the valve material.

7. An electrical construction for protection against lightning surges, a power line, an electrical instrumentality supplied from said power line and having a terminal connected to said power line, a first electrode carried by said terminal, a valve type lightning arrester comprising insulating supporting means including an insulating casing having a first and a second terminal and having valve material and an internal spark gap connected in series between said first and second terminals and located within said casing, a second electrode carried by said first terminal of said lightning arrester and spaced from said first electrode and constituting with said first electrode a large external spark gas as compared with said internal spark gap, and a tensioned fuse link normally bridging said large external spark gap, the large external spark gap being arranged to stay in series circuit with the internal spark gap for both a lightning surge of normal value and for an abnormal lightning surge of sutficient value to cause clinkering of the valve material, and the fuse link being arranged to melt upon the occurrence of an abnormal lightning surge of a value suificient to cause clinkering of the valve material.

References Cited in the file of this patent UNITED STATES PATENTS 1,939,371 Spurgeon Dec. 12, 1933 2,003,298 Lemmon June 4, 1935 2,158,859 Horikoshi May 16, 1939 2,490,952 Earle Dec. 13, 1949 UNITED STATES PATENT OFFICE CERTIFICATION OF CORRECTION Patent No 2,971,132 February 7, 1961 William H. Nash It is hereby certifiedthat error appears in the above numbered patent requiring correction and that the said Letters Patent should read as correc ted below Column 4, line 70 before "gap" insert M spark column 6, line 36, for "gas" read M gap Signed and sealed this 18th day of July 1961 (SEAL) Attest:

ERNEST W. SWIDER DAVID L. LADD Attfisting Offi er Commissioner of Patents UNITED STATES PATENT OFFICE CERTIFICATION OF CORRECTION Patent No, 2,971, 132 February 7, 1961 William- H. Nash It is hereby certified'that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 4, line 70, before "gap" insert spark column 6, line 36, for "gas" read gap =0 Signed and sealed this 18th day of July 1961 (SEAL) Attest:

ERNEST W. SWIDER DAVID L. LADD Attfisting Offi fir Commissioner of Patents 

